Pre-Descemet Endothelial Keratoplasty With Infant Donor Corneas: A Prospective Analysis

Outcomes of Pre-Descemet Endothelial Keratoplasty for Failed Therapeutic Penetrating Keratoplasty

PURPOSE

The aim of this study was to analyze the outcomes of pre-Descemet endothelial keratoplasty (PDEK) for failed therapeutic penetrating keratoplasty.

METHODS

This was a retrospective, interventional study that involved 12 eyes of 12 patients with failed therapeutic penetrating keratoplasty that underwent PDEK. All cases had a minimum follow-up of 12 months. The main outcome measures were best-corrected visual acuity, graft clarity, endothelial cell density loss, and graft survival. Corneal clarity was graded on a scale from 0 to 4, where grade 4 denoted an absolutely clear cornea and grade 0 denoted a totally opaque cornea. Three cases underwent PDEK, 6 cases PDEK with phacoemulsification, and 3 cases underwent PDEK with pupilloplasty.

RESULTS

The mean follow-up period for all cases was 18.5 ± 4.9 months. The mean preoperative and postoperative best-corrected visual acuity (in Snellen decimal equivalent) was 0.02 ± 0.01 and 0.54 ± 0.17, respectively, at the last follow-up. Postoperatively, corneal clarity grade 4 was present in 9 eyes, grade 3 in 2 eyes, and grade 2 in 1 eye. Mild subepithelial haze was noted in 2 eyes. The percentage of endothelial cell density loss was 28.2% ± 10.6%. No correlation was observed between the postoperative graft clarity and preoperative specular count (r = -0.021, P = 0.512). Rebubbling was performed for 1 eye that developed partial graft detachment in the first postoperative week. One patient had an episode of rejection that was managed with systemic and topical steroids.

CONCLUSIONS

In patients with failed therapeutic penetrating keratoplasty, PDEK can be a useful alternative for visual rehabilitation as it demonstrates favorable visual outcomes with a good graft survival rate.

Optimized Kalinnikov-Dinh technology for effective pre-Descemet's endothelial keratoplasty (PDEK) graft preparation and preservation

We report an optimized Kalinnikov-Dinh technology for pre-Descemet's endothelial keratoplasty (PDEK) that involves the use of a ring fixator, base, 30G needle connected to a 5-ml syringe with a spring-loaded plunger, and storage media. Our method allows to minimize graft preparation failure and preserves the PDEK graft efficiently, by reducing complications associated with the formation of type 1 big bubbles, including bubble rupture, perforation of Descemet's membrane and endothelium, and formation of type 2 or mixed type of big bubbles, and may contribute to increasing the number of surgeons performing PDEK around the globe.

The pre-Descemet's layer (Dua's layer, also known as the Dua-Fine layer and the pre-posterior limiting lamina layer): Discovery, characterisation, clinical and surgical applications, and the controversy

The pre-Descemet's layer/Dua's layer, also termed the Dua-Fine layer and the pre-posterior limiting lamina layer, lies anterior to the Descemet's membrane in the cornea, is 10 μm (range 6-16) thick, made predominantly of type I and some type VI collagen with abundant elastin, more than any other layer of the cornea. It has high tensile strength (bursting pressure up to 700 mm of Hg), is impervious to air and almost acellular. At the periphery it demonstrates fenestrations and ramifies to become the core of the trabecular meshwork, with implications for intraocular pressure and glaucoma. It has been demonstrated in some species of animals. The layer has assumed considerable importance in anterior and posterior lamellar corneal transplant surgery by improving our understanding of the behaviour of corneal tissue during these procedures, improved techniques and made the surgery safer with better outcomes. It has led to the innovation of new surgical procedures namely, pre-Descemet's endothelial keratoplasty, suture management of acute hydrops, DALK-triple and Fogla's mini DALK. The discovery and knowledge of the layer has introduced paradigm shifts in our age old concepts of Descemet's membrane detachment, acute corneal hydrops in keratoconus and Descemetoceles, with impact on management approaches. It has been shown to contribute to the pathology and clinical signs observed in corneal infections and some corneal dystrophies. Early evidence suggests that it may have a role in the pathogenesis of keratoconus in relation to its elastin content. Its contribution to corneal biomechanics and glaucoma are subjects of current investigations.

Comparison of Pre-Descemet Endothelial Keratoplasty and Descemet Membrane Endothelial Keratoplasty in Endothelial Decompensation

PURPOSE

The purpose of this study was to compare the outcomes of pre-Descemet endothelial keratoplasty (PDEK) and Descemet membrane endothelial keratoplasty (DMEK) in cases of endothelial decompensation.

METHODS

This was a prospective, randomized, interventional study conducted at a tertiary eye hospital in North India. Thirty eyes of 28 patients with corneal decompensation were randomly subjected to PDEK (n = 15 eyes) and DMEK (n = 15 eyes). Preoperative demographic details, surgical indications, uncorrected distance visual acuity, corrected distance visual acuity, contrast sensitivity, anterior and posterior segment details, intraocular pressure, central corneal thickness, endothelial cell count, and corneal aberrometry tracing on wavefront analysis were recorded. Patients were followed up for 6 months postsurgery. Visual and graft survival outcomes were assessed.

RESULTS

Intraoperatively, a surgeon reported better ease of preparation and intracameral handling with PDEK grafts. Both groups showed comparable improvement in visual acuity, contrast, and high-order aberrations. A decrease in central corneal thickness was significantly higher in DMEK (196 ± 26 vs. 140 ± 14 μm) patients. DMEK grafts were significantly thinner than PDEK grafts at the 6-month follow-up (16 ± 2.17 vs. 27.2 ± 1.93 μm). Endothelial cell loss (35% in DMEK vs. 33.4% in PDEK, P = 0.48) and rise of intraocular pressure (from 15.33 ± 2.85 mm Hg to 15.53 ± 2.2 mm Hg in the DMEK group vs. from 14.6 ± 1.99 mm Hg to 16.2 ± 1.43 mm Hg in the PDEK group) were comparable. Rebubbling rates were higher in the DMEK group (3/15, 20%) compared with the PDEK group (1/15, 6.66%; P = 0.165).

CONCLUSIONS

DMEK and PDEK were comparable for both quantitative and qualitative visual outcomes and anatomically for graft survival at the 6-month follow-up.

[A new surgical approach to pre-Descemet's endothelial keratoplasty]

PURPOSE

The study aimed to develop new surgical methods of obtaining and preserving pre-Descemet's endothelial keratoplasty (PDEK) graft in order to reduce the loss of donor material.

MATERIAL AND METHODS

The study was conducted on 30 sclerocorneal discs, which were divided into three groups. The first group consisted of 10 sclerocorneal discs to which the standard PDEK graft preparation technique was applied. The second group consisted of 10 sclerocorneal discs, where the PDEK graft preparation was done using the optimized method 1 involving the KD Ring fixator, KD Base for PDEK, KD-30G needle with 5 mL syringe connected to the spring-load plunger, a preservative solution. The third group consisted of 10 sclerocorneal discs with PDEK graft prepared using the optimized method 2, which differed from the optimized method 1 in additional use of the KD artificial chamber for PDEK. When successfully acquiring the type-1 "big bubble", the dissected PDEK graft was preserved for further use in clinical practice using our own technique.

RESULTS

In the first group, formation of the type-1 «big bubble» was achieved only in 5 out of 10 donor corneas (50%). Bubble ruptures happened in 4 cases (40%) and type-2 «big bubble» occurred in 1 case (10%). In the second group (optimized method 1) the type-1 «big bubble» was achieved in 9 cases (90%), while in the third group (optimized method 2) the type-1 «big bubble» was achieved in 10 cases (100%), proving the effectiveness of our PDEK graft preparation technique.

CONCLUSION

We presented a novel surgical approach for acquiring and preserving PDEK graft that minimizes almost all the difficulties that surgeons face, including bubble rupture during pneumodissection and hydrodissection, formation of type-2 and mixed type bubble, and obtaining a PDEK graft of the required size; the details of the surgical technique have been refined. The proposed technique for graft preparation and preservation can be easily implemented in eye banks and is convenient for clinical practice.

Descemet's stripping automated endothelial keratoplasty using donor tissue from an 83-day-old infant

Purpose:

To report a case of Descemet stripping automated endothelial keratoplasty (DSAEK) combined with phacoemulsification in an adult recipient using endothelial graft from an 83-day-old infant donor.

Methods:

A corneoscleral button was obtained from an infant donor and a DSAEK graft was prepared using a microkeratome. In comparison to the standard technique of DSAEK graft preparation some modifications were made in order to avoid inadvertent perforation, as the donor cornea had a very spherical shape, probably due to the very young age of the donor. The DSAEK graft was transplanted to the left eye of a 68-year-old woman suffering from Fuchs' endothelial dystrophy. Her preoperative best-corrected visual acuity (BCVA) in that eye was 20/100 and central corneal thickness 831 μm.

Results:

An uneventful DSAEK combined with phacoemulsification was performed. The main complication noted was detachment of the peripheral part and contraction of the corneal graft, observed two months after the procedure. The implanted tissue remained centrally attached with a BCVA of 20/40, 3 years postoperatively.

Conclusion:

This case report highlights the difficulties emerging from preparation and implantation using an endothelial graft tissue from the youngest ever reported donor.

Descemet Membrane Endothelial Keratoplasty and Bowman Layer Transplantation: An Anatomic Review and Historical Survey

For nearly a century, the definitive treatment of many corneal dystrophies and ectactic disorders was limited to penetrating keratoplasty, but over the past 2 decades, a surge of surgical innovation has propelled the treatment of many corneal diseases to more targeted approaches with significantly better visual outcomes. Anterior stromal diseases were first changed through endothelial-sparing techniques, such as deep anterior lamellar keratoplasty, but have more recently transitioned to stromal-sparing approaches. Ultraviolet corneal crosslinking strengthens the cornea and halts progression of keratoconus in >90% of cases. Intracorneal ring segment and corneal allogenic ring segment implantation offer methods to flatten ectatic corneas. However, Bowman layer transplantation - inlay and more recently onlay techniques - has shown promise for treating advanced keratoconus and preventing keratoplasty. The advent of endothelial keratoplasty radically changed the treatment of corneal endothelial dysfunction, and Descemet membrane endothelial keratoplasty specifically offers an average postoperative visual acuity of 20/25 (0.8) with only 8.8% of grafts requiring retransplantation in the first 5 years. Here, we review the rapid innovations for surgical treatment of corneal diseases, spanning from endothelial keratoplasty and endothelial regeneration to anterior lamellar keratoplasty and stromal augmentation, highlighting key steps which may be moving us closer to a "postkeratoplasty" world.

Pre-Descemet's endothelial keratoplasty: a simple, Descemet's membrane scoring technique for successful graft preparation

PURPOSE

Pre-Descemet's endothelial keratoplasty (PDEK) donor tissue preparation involves the intrastromal injection of air to create a type 1 big bubble (BB) and avoidance of the creation of a type 2 BB. The purpose of this study was to design and test a technique to consistently creates a type 1 BB without risk of creating a type 2 BB.

METHODS

A prospective matched study with 64 human donor sclerocorneal discs, which were not suitable for corneal transplantation, was conducted. The corneas were divided into two groups, of which 32 were subjected to the standard technique of preparing the PDEK donor tissue (group 1, control) and 32 new technique, where in the donor Descemet's membrane was scored with a Sinskey hook. Frequency of occurrence of different types of BB was compared and statistically analysed.

RESULTS

With the standard technique (group 1), type 1 BB occurred in 53.1%, type 2 BB in 34.4% and mixed BB in 12.5% of samples. With the scoring technique (group 2), a type 1 BB occurred in 100% of the samples. No type 2 or mixed BB occurred in any case in group 2. The difference in creation of a type 1BB between the two groups was statistically significant (p=0.00).

CONCLUSION

The scoring technique is a simple, inexpensive and reproducible option to consistently achieve a type 1 BB to prepare PDEK graft tissue. The next step would be to study the clinical outcomes of PDEK performed with tissue obtained by the scoring technique.

Characterization of Endothelial Cell Loss in Pre-Descemet Endothelial Keratoplasty Graft Preparation

PURPOSE

To characterize the pattern and factors affecting endothelial cell loss (ECL) in pre-Descemet Endothelial Keratoplasty (PDEK) graft preparation.

METHODS

A prospective study was performed to characterize the pattern of ECL and the impact of inflation pressure in PDEK. Donor corneas were randomized to inflation with air versus Optisol GS storage media. PDEK preparation was performed under continuous pressure monitoring. Trypan blue was used to grade the tissue as acceptable (<25% ECL) or unacceptable (≥25% ECL). Rate of unacceptable ECL was correlated with injection media type and inflation pressure. A retrospective study was then performed of all attempted PDEK preparations at Lions Gift of Sight to evaluate impact of donor tissue factors on ECL. Donor age and tissue preservation time were evaluated and correlated with ECL with PDEK bubbling.

RESULTS

Twenty-five corneas were tested prospectively. A reticular pattern of ECL that varied in severity occurred with bubbling. There was no difference in peak inflation pressure or mean expansion pressure between air (706.0, 510.7 mm Hg) and Optisol GS (852.9, 653.0 mm Hg). Increasing peak inflation pressure and mean expansion pressure were associated with an increased risk for unacceptable ECL. On retrospective evaluation of 131 attempted PDEKs, only 44.0% of cases with successful bubbles had acceptable endothelium after processing. Increasing donor age and decreasing preservation time were associated with increased rates of acceptable endothelium.

CONCLUSIONS

PDEK processing can result in a reticular pattern of ECL. Higher inflation pressures are associated with greater ECL. Older donor tissues with shorter preservation times might be preferable for PDEK.

Optimizing pre-Descemet endothelial keratoplasty technique

Pre-Descemet endothelial keratoplasty (PDEK) is an alternative technique to Descemet membrane endothelial keratoplasty (DMEK). The preparation of PDEK tissue by pneumatic dissection is simple and reproducible. The PDEK clamp helps to consistently obtain a type 1 big bubble. The mean size of type 1 big bubble is 7.255 ± 0.535 × 6.745 ± 0.668 mm. The volume of air required to obtain type 1 big bubble is 0.14 to 0.37 mL. Dissection of PDEK tissue can be achieved by trephination or manual excision. Insertion of tissue into the recipient eye can be by injection or pulling. Unfolding techniques used for PDEK are similar to those used in DMEK. Unlike DMEK, PDEK tissue is easier to handle and unscroll and allows use of younger donors. It could help surgeons converting to endothelial keratoplasty, with significant advantages in preparation, handling, and unscrolling in the eye.

Lamellar keratoplasty techniques

Lamellar keratoplasty (LK) has revolutionized corneal graft surgery in several ways. Deep anterior LK (DALK) has eliminated risk of failure due to endothelial rejection. Endothelial keratoplasty (EK) has almost eliminated induced astigmatism and the “weak” graft–host junction as seen with penetrating keratoplasty (PK) and also reduced the risk of endothelial rejection. LK provided new insights into posterior corneal anatomy that led to better understanding and performance of DALK and to the development of another EK procedure, namely pre-Descemet's EK (PDEK). Surgical procedures for LK were further refined based on the improved understanding and are able to deliver better surgical outcomes in terms of structural integrity and long-term patient satisfaction, reducing the need of further surgeries and minimizing patient discomfort. In most specialist centers, anterior lamellar techniques like DALK and EK techniques like Descemet's stripping EK (DSEK) and Descemet's membrane EK (DMEK) have replaced the full-thickness PK where possible. The introduction of microkeratome, femtosecond laser, and PDEK clamp have made LK techniques easier and more predictable and have led to the innovation of another LK procedure, namely Bowman membrane transplant (BMT). In this article, we discuss the evolution of different surgical techniques, their principles, main outcomes, and limitations. To date, experience with BMT is limited, but DALK has become the gold standard for anterior LK. The EK procedures too have undergone a rapid transition from DSEK to DMEK and PDEK emerging as a viable option. Ultrathin-DSEK may still have a role in modern EK.

Use of Pressurized Air Infusion For Pre Descemet's Endothelial Keratoplasty (PDEK) - The Air Pump Assisted PDEK Technique

Purpose:

To assess the advantages offered by the air pump assisted PDEK technique that utilizes pressurized Anterior Chamber (AC) air infusion.

Methods:

Pressurized air infusion was provided through an anterior chamber maintainer connected to the fluid air exchange system of a posterior vitrectomy machine during surgery.

Results:

Pressurized air infusion within the AC helped perform Descemetorhexis, prevented bleeding during Peripheral Iridectomy (PI) and synechiolysis, prevented oozing of blood from peripheral corneal neovascularization into the AC and thus helped maintain a non-fibrinous AC environment. In addition, it helped in precise graft manipulation, centration, edge unfolding and unwrinkling after it was floated against the stroma as well as faster graft adhesion. It also prevented AC depth fluctuations during intra-cameral maneuvers and prevented intra-operative as well as post-operative graft detachment.

Conclusions:

This technique makes several steps of surgery easier and improves graft adhesion.

Phacoemulsification with single-pass four-throw pupilloplasty and pre-Descemet's endothelial keratoplasty for management of cosmetic iris implant complication

Placement of an anterior chamber iris implant for cosmetic reasons has been associated with development of various complications. Even after the implant has been explanted from the eye, it leaves a trail of after effects that necessitate surgical management. We describe a technique that comprises of performing phacoemulsification with single-pass four-throw pupilloplasty and a pre-Descemet's endothelial keratoplasty procedure for this eye with cosmetic iris implant complication.

Young donor-graft assisted endothelial keratoplasty (PDEK/DMEK) with epithelial debridement for chronic pseudophakic bullous keratopathy

OBJECTIVE

The aim of this study was to describe the applicability and report visual outcomes for the treatment of subepithelial fibrosis and anterior stromal scarring in cases of chronic pseudophakic bullous keratopathy (PBK) with epithelial debridement and endothelial keratoplasty (EK) (pre-Descemet endothelial keratoplasty [PDEK]; Descemet membrane endothelial keratoplasty [(DMEK]) using young donor tissue.

DESIGN

Prospective, single-centre, interventional study.

PARTICIPANTS

6 cases with chronic PBK (> 1 year duration).

METHODS

Case 1 underwent PDEK with glued intraocular lens (IOL) as a single-stage procedure, whereas cases 2 and 3 underwent glued IOL followed by DMEK and PDEK, respectively, as a second-stage procedure. Cases 4 and 6 underwent PDEK, whereas case 5 underwent DMEK. Epithelial debridement was performed in all cases at the time of EK, and young donor grafts were used. The main outcome measures were best spectacle-corrected visual acuity, clearance of corneal scar and haze, central corneal thickness (CCT), specular microscopy, and endothelial cell count (ECC).

RESULTS

Postoperatively, all cases demonstrated significant improvement in visual acuity. The mean value of depth of subepithelial haze was 121±71.7 µm and 25.3 ± 19.8 µm in the preoperative and postoperative periods, respectively (p = 0.028). At the 1-month follow-up, the mean preoperative CCT of 676 ± 92.7 µm was reduced to 534.6 ± 21.1µm. At the 6-month follow-up, the mean ECC loss resulting from the procedure was 36.5 ± 10.4%.

CONCLUSIONS

EK with epithelial debridement performed for the treatment of chronic PBK resulted in significantly improved visual acuity to a functional level, with the clearance of subepithelial fibrosis and anterior stromal scar, in most patients.

Pre-Descemets endothelial keratoplasty: the PDEK clamp for successful PDEK

PurposeTo design and produce a clamp that enables good handling of donor sclera-corneal disks, allows air to be injected in the corneal stroma and consistently provides pre-Descemets endothelial keratoplasty (PDEK) tissue by creation of a type-1 big bubble (BB) avoiding a type-2BB by shutting the fenestrations in the periphery of the pre-Descemets layer and preventing escape of air.Patients and methodsA clamp with spring loaded handles attached to two rings of 9 mm diameter and 1 mm width with a side port for insertion of a needle for air injection was designed and produced. The clamp was tested in 20 human donor sclera-corneal disks and refined over three prototypes. The final design was used for PDEK in 8 patients.ResultsThe clamp was able to prevent any escape of air or the formation of a type-2BB. By preventing air leak, it provided better control over the volume of air injected allowing for consistent formation of a type-1BB, which could be expanded to its full diameter by advancing the tip of the needle into the bubble cavity. Centration of tissue in the clamp was important. The clamp was used successfully to obtain PDEK tissue from 8 donor sclara-corneal disks for transplant in three eyes with pseudophakic bullous keratopathy and five eyes with pseudophakia and Fuchs' endothelial dystrophy.ConclusionThe PDEK clamp is a simple and useful instrument that will give surgeons the confidence of consistently obtaining PDEK tissue with ease and without the risk of separating the Descemets membrane in a type-2BB.

Pre-Descemet's endothelial keratoplasty

Endothelial keratoplasty (EK) has supplanted the penetrating keratoplasty procedure for corneal endothelial disorders. A review of literature on pre-descemet's EK, that is, a latest iterant in EK is described along with our experiences.

Air Pump-Assisted Graft Centration, Graft Edge Unfolding, and Graft Uncreasing in Young Donor Graft Pre-Descemet Endothelial Keratoplasty

PURPOSE

To assess an air pump-assisted technique for graft centration, graft edge unfolding, and graft uncreasing while performing pre-Descemet endothelial keratoplasty (PDEK) using young donor grafts.

METHODS

Continuous pressurized air infusion was used for graft centration, graft edge unfolding, and graft unwrinkling.

RESULTS

Ten eyes of 10 patients underwent PDEK with donors aged below 40 years. In all eyes, the donor scrolled into tight scrolls. In all cases, the air pump-assisted technique was effective in positioning and centering the graft accurately and in straightening infolded graft edges and smoothing out graft creases and wrinkles. Endothelial cell loss was 38.6%. Postoperative best-corrected visual acuity at 6 months was 0.66 ± 0.25 in decimal equivalent. Continuous pressurized air infusion acted as a third hand providing a continuous pressure head that supported the graft and prevented graft dislocation as well as anterior chamber collapse during intraocular maneuvering. Adequate maneuvering space was available in all cases, and bleeding, if any, was tamponaded successfully in all cases.

CONCLUSIONS

Although very young donor grafts may be used for PDEK, they are difficult to center and unroll completely before floating against host stroma. An air pump-assisted technique using continuous pressurized air infusion allows successful final graft positioning even with very young donor corneas. It thus makes surgery easier as several key steps are made easier to handle. It additionally helps in tamponading hemorrhage during peripheral iridectomy, increasing surgical space, preventing fluctuations in the anterior chamber depth, and promoting graft adherence.

Glued Intrascleral Fixation of Intraocular Lens With Pupilloplasty and Pre-Descemet Endothelial Keratoplasty: A Triple Procedure

PURPOSE

To describe a surgical approach of glue-assisted intrascleral fixation of an intraocular lens (IOL) with pupilloplasty and pre-Descemet endothelial keratoplasty as a single-stage procedure.

METHODS

Glue-assisted intrascleral fixation of an IOL is performed initially because it helps to secure the IOL fixation, followed by pupilloplasty that imparts stability to the anterior chamber and prevents air diversion into the vitreous cavity, thereby facilitating the pre-Descemet endothelial keratoplasty procedure that is performed to complete the surgical repair.

RESULTS

The procedure was performed in 5 eyes of 5 patients, and the donor age ranged from 9 months to 65 years. There was a significant change in the uncorrected (P = 0.034) and corrected (P = 0.043) distance visual acuities in the postoperative period. The mean graft size was 7.6 ± 0.4 mm (range, 7-8 mm). The mean preoperative and postoperative specular endothelial counts were 2788 ± 204 cells per square millimeter and 1898 ± 90 cells per square millimeter, respectively. No incidence of primary graft failure or graft rejection during the entire follow-up period was reported in any of the eyes.

CONCLUSIONS

The combined procedure serves as an effective method in select cases of endothelial decompensation that require a secondary IOL implantation or an IOL exchange with good postoperative results.

Scrolling Characteristics of Pre-Descemet Endothelial Keratoplasty Tissue: An Ex Vivo Study

PURPOSE

To evaluate the scrolling propensity of pre-Descemet endothelial keratoplasty (PDEK) tissue and to compare it with each component of the PDEK tissue, namely the pre-Descemet layer (Dua's layer [PDL]) and the Descemet membrane (DM).

DESIGN

Experimental laboratory investigation.

METHODS

Fourteen human donor sclerocorneal discs in which a type 1 big bubble was obtained by stromal injection of air were studied. The wall of the type 1 big bubble was excised and its grade of scrolling noted. The components of the wall (ie, the DM and PDL) were then separated and the scrolling of each was individually graded. Statistical comparison of the grade of scrolling of each layer and correlation with age was carried out; 25-μm slices of anterior and posterior stroma obtained with the femtosecond laser from 4 control samples were used for comparison. The main outcome measure was the grade of scrolling of PDEK tissue in comparison with PDL and DM.

RESULTS

Mean donor age was 67 years. The mean grade of the scroll formed by PDEK tissue was1.6 compared to 0.64 for PDL alone and 3.6 for DM alone. The difference was statistically significant. No correlation between donor age and degree of scrolling for any of the tissues tested was found.

CONCLUSION

PDEK tissue scrolls less than DM. PDL scrolls the least. This demonstrates that PDL tissue splints the DM and reduces its scrolling in PDEK. This feature has relevance to tissue preparation, handling, and unscrolling in the eye during endothelial keratoplasty.